Heater



FIG. 1 is a perspective view of a heater showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a side elevational view thereof, taken from the left of FIG. 1; and

FIG. 7 is a side elevational view thereof, taken from the right of FIG. 1. 

The ornamental design for a heater, as shown. 